*Update 8/30* Help me diagnose my SBR issues...

Tim

Tim

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10.5" Ballistic Advantage BA Hanson barrel
Carbine length gas tube
Gas block is an Odin Works adjustable - have tried wide open, 1-click off closed and everything in between
Standard carbine spring
Have tried 2.8, 4.5 and 5 oz buffers
Standard BCG and bolt, nothing special

The gun cycles properly when suppressed (SiCo Omega), but will occasionally fail on LRBHO.

The gun fails to cycle properly on every round when not suppressed. Typically it's a fail with feeding the next round. Sometimes it will fail to eject, but the FTF is much more common.

Same issue with 55gr --> 77gr loads.

What would your next step be?
I'm thinking I'll tear it apart and replace the gas block, get a fresh recoil spring and maybe an Xtra power spring while I'm at it.

Do you think I ought to try different buffer weights as well?
 
I’d look at the gas port and maybe open that up. But mostly I want to hear what the experts say.
 
Tim said:
10.5" Ballistic Advantage BA Hanson barrel
Carbine length gas tube
Gas block is an Odin Works adjustable - have tried wide open, 1-click off closed and everything in between
Standard carbine spring
Have tried 2.8, 4.5 and 5 oz buffers
Standard BCG and bolt, nothing special

The gun cycles properly when suppressed (SiCo Omega), but will occasionally fail on LRBHO.

The gun fails to cycle properly on every round when not suppressed. Typically it's a fail with feeding the next round. Sometimes it will fail to eject, but the FTF is much more common.

Same issue with 55gr --> 77gr loads.

What would your next step be?
I'm thinking I'll tear it apart and replace the gas block, get a fresh recoil spring and maybe an Xtra power spring while I'm at it.

Do you think I ought to try different buffer weights as well?
Click to expand...

Sounds under gassed to me. Is the gas port lined up right? Or is the gas port the right size?


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Zbizzle911 said:
Sounds under gassed to me. Is the gas port lined up right? Or is the gas port the right size?


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Click to expand...


Not sure...I need to get it torn down. Likely one night this week.
 
Zbizzle911 said:
Is the gas block a set screws type? If so did you simple the barrel?


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Click to expand...


Honestly...I don't recall if I dimpled the barrel. I built this one ~18 months ago and it just doesn't get shot unsuppressed much at all. So, the issue has been masked. I'm getting ready for a Run-n-Gun and want to carry this SBR instead of my heavy 18" rifle.
 
Zbizzle911 said:
Sounds under gassed to me. Is the gas port lined up right? Or is the gas port the right size?
Click to expand...
That was my initial thought before reading any replies. Gas block not perfectly lined up with gas port.
 
Carbon buildup in the adjustable block I bet. Gas system gets really dirty with suppressor use. Take the block off, soak it and clean it and the port/tube well.
 
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This was my thought as well.
Carbon could be choking gas.
On the other end seems like stiffer spring is going the wrong way?

bigfelipe said:
Carbon buildup in the adjustable block I bet. Gas system gets really dirty with suppressor use. Take the block off, soak it and clean it and the port/tube well.
Click to expand...
 
the dwell time on a 10.5 carbine is already pretty short so you are likely under gassed with the addition of an adjustable block. especially if the agb is tuned to the can.

Hanson barrels are historically conservatively gassed.

id put the BA block that came with the barrel back on and run it.

then you can go up in buffer weight and/or spring weight to offset the added gas from the can. (better still, go A5!)

check your gas rings as well if this bcg served in another upper before this one.

my .02
 
Last edited:
The 10.5” Hansons have a .0635” gas port. That’s pretty small for a 10.5”.

If the gas block is open all the way like you stated (just reconfirm it for simplicity’s sake) and if it is also properly lined up and not clogged, you may need to open the port up just a hair.

Their 11.5” Hanson has a .0730” port, so if all of the above checks out, I’d open the port up at small increments. I’d probably try .0670” (#51 bit / 1.70mm) and then a #50 .070”/ 1.78mm bit. I bet it’ll be running with the first one
 
I'd open the gas port to .075"-.080" and regulate the gas back down with the AGB.



Also,
What magazine(s) are you using?
As a suggestion, try some HK steel mags for your SBR. They are true 30 round magazines, have a great follower spring in them, and the feed lips stay consistent. Your rifle will love them!
 
So I completely tore the rifle down. It was filthy. I mean, embarrassingly filthy.

Soaked the gas block in solvent
Scrubbed the heck out the receiver
Soaked the gas tube
Scrubbed it all, blew it out with air compressor and let it all dry.

Reassembled.

I got out yesterday and adjusted the gas all the way out. Worked great!

Unsuppressed.

Dialed the gas down in small increments to find a sweet spot. Ran 2-3 magazines through it with no trouble.

Happy happy!

Moved on to other rifles for a while.

As I was packing up, I had a partial magazine still loaded. Ran that through, and I’m back to having issues. I’d get ejection and trigger reset but would not feed the next round.
 
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